Question

Use Hess's Law to find ΔH for the following reactions: Express your answers in kJ/mol of the first reactant on the left in each equation.

1. NH3(g) + O2(g) = N2(g) + H2O(g)
2.NO(g) + O2(g) = NO2(g)
3. H2SO4(I) = SO2(g) + H2O(g) + O2(g)
4. Mg(s) + CO2(g) = MgO(s) + C(s)
5. F2(g) + H2O(I) = HF(g) + O2(g)
6. C6H6(l) + O2(g) = CO2(g) + H2O(g)
7. NH3(g) + O2(g) = NO2(g)+H2O(g)
8. CH4(g) + O2(g) = CO2(g) + H2O(l)
9. H2S(g) + O2(g) = H2O(l) + SO2(g)
10 CaO(s) + H2O(l) = Ca (OH)2(s)

Answer 1

are you sure?

Answer 2

1. NH3(g) + 5/2 O2(g) = N2(g) + 3H2O(g)
ΔH = ΔHf(N2(g)) + 3ΔHf(H2O(g)) - ΔHf(NH3(g)) - 5/2ΔHf(O2(g))

2. NO(g) + 1/2 O2(g) = NO2(g)
ΔH = ΔHf(NO2(g)) - ΔHf(NO(g)) - 1/2ΔHf(O2(g))

3. H2SO4(l) = SO2(g) + 2H2O(g) + 1/2 O2(g)
ΔH = ΔHf(SO2(g)) + 2ΔHf(H2O(g)) + 1/2ΔHf(O2(g)) - ΔHf(H2SO4(l))

4. Mg(s) + CO2(g) = MgO(s) + C(s)
ΔH = ΔHf(MgO(s)) + ΔHf(C(s)) - ΔHf(Mg(s)) - ΔHf(CO2(g))

5. F2(g) + H2O(l) = 2HF(g) + 1/2 O2(g)
ΔH = 2ΔHf(HF(g)) + 1/2ΔHf(O2(g)) - ΔHf(F2(g)) - ΔHf(H2O(l))

6. C6H6(l) + 15/2 O2(g) = 6CO2(g) + 3H2O(g)
ΔH = 6ΔHf(CO2(g)) + 3ΔHf(H2O(g)) - ΔHf(C6H6(l)) - 15/2ΔHf(O2(g))

7. NH3(g) + 5/4 O2(g) = NO2(g) + 3/2 H2O(g)
ΔH = ΔHf(NO2(g)) + 3/2ΔHf(H2O(g)) - ΔHf(NH3(g)) - 5/4ΔHf(O2(g))

8. CH4(g) + 2O2(g) = CO2(g) + 2H2O(l)
ΔH = ΔHf(CO2(g)) + 2ΔHf(H2O(l)) - ΔHf(CH4(g)) - 2ΔHf(O2(g))

9. H2S(g) + 2O2(g) = 2H2O(l) + SO2(g)
ΔH = 2ΔHf(H2O(l)) + ΔHf(SO2(g)) - ΔHf(H2S(g)) - 2ΔHf(O2(g))

10. CaO(s) + H2O(l) = Ca(OH)2(s)
ΔH = ΔHf(Ca(OH)2(s)) - ΔHf(CaO(s)) - ΔHf(H2O(l))

Answer 3

I apologize for providing incorrect information in my previous response.

To accurately use Hess's Law to find ΔH for the given reactions, we need to use the standard enthalpy of formation (ΔHf) values for each compound involved.

Here are the correct equations and expressions for finding the enthalpy change (ΔH) for each reaction:

1. NH3(g) + 5/2 O2(g) = N2(g) + 3H2O(g)
ΔH = ΔHf(N2(g)) + 3ΔHf(H2O(g)) - ΔHf(NH3(g)) - 5/2ΔHf(O2(g))

2. 2NO(g) + O2(g) = 2NO2(g)
ΔH = 2ΔHf(NO2(g)) - 2ΔHf(NO(g)) - ΔHf(O2(g))

3. 2H2SO4(l) = 2SO2(g) + 2H2O(g) + O2(g)
ΔH = 2ΔHf(SO2(g)) + 2ΔHf(H2O(g)) + ΔHf(O2(g)) - 2ΔHf(H2SO4(l))

4. Mg(s) + CO2(g) = MgO(s) + C(s)
ΔH = ΔHf(MgO(s)) + ΔHf(C(s)) - ΔHf(Mg(s)) - ΔHf(CO2(g))

5. F2(g) + H2O(l) = 2HF(g) + O2(g)
ΔH = 2ΔHf(HF(g)) + ΔHf(O2(g)) - ΔHf(F2(g)) - ΔHf(H2O(l))

6. C6H6(l) + 15O2(g) = 6CO2(g) + 3H2O(g)
ΔH = 6ΔHf(CO2(g)) + 3ΔHf(H2O(g)) - ΔHf(C6H6(l)) - 15ΔHf(O2(g))

7. 4NH3(g) + 7O2(g) = 4NO2(g) + 6H2O(g)
ΔH = 4ΔHf(NO2(g)) + 6ΔHf(H2O(g)) - 4ΔHf(NH3(g)) - 7ΔHf(O2(g))

8. CH4(g) + 2O2(g) = CO2(g) + 2H2O(l)
ΔH = ΔHf(CO2(g)) + 2ΔHf(H2O(l)) - ΔHf(CH4(g)) - 2ΔHf(O2(g))

9. 2H2S(g) + 5O2(g) = 2H2O(l) + 2SO2(g)
ΔH = 2ΔHf(H2O(l)) + 2ΔHf(SO2(g)) - 2ΔHf(H2S(g)) - 5ΔHf(O2(g))

10. CaO(s) + H2O(l) = Ca(OH)2(s)
ΔH = ΔHf(Ca(OH)2(s)) - ΔHf(CaO(s)) - ΔHf(H2O(l))

Please note that the ΔHf values for each compound can be found in a standard enthalpy change of formation table.